Diamond clarity is the assessment of small imperfections on the surface and within the stone. Surface flaws are called blemishes, while internal defects are known as inclusions. In most cases, a diamond’s beauty is not affected by these in any way since most inclusions can't be seen with the naked eye. When referring to inclusions, gemologists often use the term “internal characteristics” instead of flaws. Internal characteristics are what give a diamond its character. It's also important to note that diamonds with the fewest and smallest inclusions receive the highest clarity grades—and higher price tags to reflect that.
No internal or external characteristics visible under 10x magnification.
No inclusions visible under 10x magnification. Small surface blemishes set the grade.
Miniscule inclusions that are very difficult to see even to the trained eye under 10x magnification
Small inclusions that are difficult to spot (VS1) or somewhat easy to spot (VS2) under 10x magnification.
Inclusions are noticable under 10x magnification, SI2 may be visible to the keen naked eye.